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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1575-1588页

作者： Xia shen z.ikang Shuai Wen Huang Chao shen Yang shen z.John shen College of Electrical and Information Engineering Hunan UniversityChangsha 410082China Department of Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616 USA

Bidirectional interlinking converter(BIC)is the core equipment in a hybrid AC/DC microgrid connected between AC and DC ***,the variety of control modes and flexible bidirectional power flow complicate the influence of AC faults on BIC itself and on DC sub-grid,which potentially threaten both converter safety and system *** study first investigates AC fault influence on the BIC and DC bus voltage under different BIC control modes and different pre-fault operation states,by developing a mathematical model and equivalent sequence ***,based on the analysis results,a general accommodative current limiting strategy is proposed for BIC without limitations to specific mode or operation *** amplitude is predicted and constrained according to the critical requirements to protect the BIC and relieving the AC fault influence on the DC bus *** with conventional methods,potential current limit failure and distortions under asymmetric faults can also be ***,experiments verify feasibility of the proposed method.

关键词： Bidirectional interlinking converter current limiting fault characteristic hybrid AC/DC microgrid variation/oscillation of DC bus voltage

Stability Investigation and Improvement for DC Cascade Systems with Simplified Impedance-based Stability Criterion

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1044-1052页

作者： Junbin Fang z.ikang Shuai Yang Li z.ibing Wang Xiangyang Wu Xia shen z.John shen College of Electrical and Information Engineering Hunan UniversityChangsha 410082China Renewable Energy Department of China Electric Power Research Institute Beijing 100192China Department of Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616USA IEEE

In DC distributed power systems(DPSs),the complex impedance interactions possibly lead to DC bus voltage oscillation or *** previous research,the stability analysis of DPSs is implemented based on mathematical analysis in control *** specific mechanisms of the instability of the cascade system have not been intuitively *** this paper,the stability analysis of DPSs based on the traditional Nyquist criterion is simplified to the resonance analysis of the seriesconnected port impedance(z.R+jX)of source and load *** reveals that the essential reason for impedance instability of a DC cascade system is that the negative damping characteristic(Rz.ro-crossing *** simplified stability criterion for DC cascade systems can be concluded as:in the negative damping frequency ranges(Rz.ro-crossing point of the reactance component(i.e.,X=0).According to the proposed stability criterion,the oscillation modes of cascade systems are classified.A typical one is the internal impedance instability excited by the negative damping,and the other one is that the external disturbance amplified by negativity in a low stability ***,the impedance reshaping method for stability improvement of the system can be further *** validity of the simplified criterion is verified theoretically and experimentally by a positive damping reshaping method.

关键词： DC cascaded system,impedance model impedance reconstruction stability criterion

Asymmetrical Fault Current Calculation Method and Influencing Factors Analysis of Droop-Controlled Inverters

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 562-573页

作者： Huimin z.ao z.ikang Shuai Jun Ge An Luo Weimin Wu z.John shen College of Electrical and Information Engineering Hunan UniversityChangsha 410006China Electrical Engineering Department Shanghai Maritime UniversityShanghai 201306China Department of Electrical and Computer Engineering Ilinois Institute of TechnologyChicagoIL 60616 USA

Since the fault dynamic of droop-controlled inverter is different from synchronous generators (SGs), protection devices may become invalid, and the fault overcurrent may damage power electronic devices and threaten the safety of the microgrid. Therefore, it is imperative to conduct a comprehensive fault analysis of the inverter to guide the design of protection schemes. However, due to the complexity of droop control strategy, existing literatures have simplified asymmetric fault analysis of droop-controlled inverters to varying degrees. Therefore, accurate fault analysis of a droop-controlled inverter is needed. In this paper, by analyz.ng the control system, an accurate fault model is established. Based on this, a calculation method for instantaneous asymmetrical fault current is proposed. In addition, the current components and current characteristics are analyz.d. It was determined that fault currents are affected by control loops, fault types, fault distance and nonlinear limiters. In particular, the influences of limiters on the fault model, fault current calculation and fault current characteristics were analyz.d. Through detailed analysis, it was found that dynamics of the control loop cannot be ignored, the fault type and fault distance determine fault current level, and part of the limiters will totally change the fault current trend. Finally, calculation and experimental results verify the correctness of the proposed method.

关键词： Asymmetrical fault analysis droop control fault current calculation method limiter transient fault characteristics

Effects of exosomes from mesenchymal stem cells on functional recovery of a patient with total radial nerve injury: A pilot study

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World Journal of Stem Cells 2024年第1期16卷 19-32页

作者： ErdinçCivelek Serdar Kabatas eyüp Can Savrunlu Furkan Diren Necati Kaplan Demet Ofluoğlu Erdal Karaöz Department of Neurosurgery University of Health SciencesGaziosmanpaşa Training and Research HospitalGaziosmanpaşa 34255IstanbulTurkey Department of Neurosurgery University of Health Sciences TurkeyGaziosmanpaşa Training and Research HospitalGaziosmanpaşa 34255IstanbulTurkey Center for Stem Cell&Gene Therapy Research and Practice University of Health Sciences TurkeyGaziosmanpaşa 34255IstanbulTurkey Department of Neurosurgery Nevşehir State HospitalNevşehir 50300Turkey Department of Neurosurgery Istanbul Rumeli UniversityÇorlu Reyap HospitalÇorlu 59860TekirdağTurkey Department of Physical Medicine and Rehabilitation Ofluoğlu KlinikGöztepe 34728IstanbulTurkey Liv Hospital Center for Regenerative Medicine and Stem Cell Research&Manufacturing(LivMedCell)Beşiktaş34340IstanbulTurkey Department of Histology and Embryology Istinye UniversityFaculty of MedicineZeytinburnu 34010IstanbulTurkey Istinye University Center for Stem Cell and Tissue Engineering Research and PracticeBeşiktaş34340IstanbulTurkey

BACKGROUND Peripheral nerve injury can result in significant clinical complications that have uncertain ***,there is a lack of effective pharmacological interventions for nerve damage,despite the existence of several small compounds,Despite the objective of achieving full functional restoration by surgical intervention,the persistent challenge of inadequate functional recovery remains a significant concern in the context of peripheral nerve *** To examine the impact of exosomes on the process of functional recovery following a complete radial nerve *** A male individual,aged 24,who is right-hand dominant and an immigrant,arrived with an injury caused by a knife *** cut is located on the left arm,specifically below the *** neurological examination and electrodiagnostic testing reveal evidence of left radial nerve *** sural autograft was utiliz.d for repair,followed by the application of 1 mL of mesenchymal stem cell-derived exosome,comprising 5 billion *** exosome was split into four equal volumes of 0.25 mL each and delivered microsurgically to both the proximal and distal stumps using the subepineural *** patient was subjected to a period of 180 d during which they had neurological examination and electrodiagnostic *** The duration of the patient’s follow-up period was 180 *** increasing Tinel’s sign and sensory-motor recovery were detected even at the 10th wk following nerve *** the conclusion of the 6-mo post-treatment period,an evaluation was conducted to measure the extent of improvement in motor and sensory functions of the *** assessment was based on the British Medical Research Council scale and the Mackinnon-Dellon *** results indicated that the level of improvement in motor function was classified as M5,denoting an excellent ***,the level of improvement in sensory function was classified as S3+,indicating a good *** is

关键词： Mesenchymal stem cell Exosomes Radial nerve Sural nerve

Allogeneic mesenchymal stem cells may be a viable treatment modality in cerebral palsy

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World Journal of Clinical Cases 2024年第9期12卷 1585-1596页

作者： Osman Boyalı Serdar Kabatas ErdinçCivelek Omer Oz.emir Yeliz.Bahar-Oz.emir Necati Kaplan eyüp Can Savrunlu Erdal Karaöz Department of Neurosurgery University of Health Sciences TurkeyGaziosmanpaşa Training and Research HospitalIstanbul 34360Turkey Center for Stem Cell&Gene Therapy Research and Practice University of Health Sciences TurkeyIstanbul 34360Turkey Department of Physical Medicine and Rehabilitation Health Sciences University Sultan Abdulhamid Han Training and Research HospitalIstanbul 34668Turkey Department of Neurosurgery Istanbul Rumeli UniversityÇorlu Reyap HospitalTekirdağ59860Turkey Department of Neurosurgery Nevşehir State HospitalNevşehir 50300Turkey Center for Regenerative Medicine and Stem Cell Research&Manufacturing(LivMedCell) Liv HospitalIstanbul 34340Turkey Department of Histology and Embryology Istinye UniversityFaculty of Medicineİstanbul 34010Turkey Center for Stem Cell and Tissue Engineering Research and Practice Istinye UniversityIstanbul 34340Turkey

BACKGROUND Cerebral palsy(CP)describes a group of disorders affecting movement,balance,and *** in motor functions constitute the main body of CP *** symptoms surface in early childhood and patients are affected for the rest of their ***,treatment involves various pharmacotherapies for different types of CP,including antiepileptics for epilepsy and Botox A for focal ***,none of these methods can provide full symptom *** has prompted researchers to look for new treatment modalities,one of which is mesenchymal stem cell therapy(MSCT).Despite being a promising tool and offering a wide array of possibilities,mesenchymal stem cells(MSCs)still need to be investigated for their efficacy and *** To analyz. the efficacy and safety of MSCT in CP *** Our sample consists of four CP patients who cannot stand or walk without external *** of these cases received allogeneic MSCT six times as 1×106/kg intrathecally,intravenously,and intramuscularly using umbilical cord-derived MSCs(UC-MSC).We monitored and assessed the patients pre-and post-treatment using the Wee Functional Independence Measure(WeeFIM),Gross Motor Function Classification System(GMFCS),and Manual Ability Classification Scale(MACS)*** utiliz.d the Modified Ashworth Scale(MAS)to measure *** We found significant improvements in MAS scores after the intervention on both *** months:Rightχ^(2)=4000,P=0.046,leftχ^(2)=4000,P=0.046;four months:Rightχ^(2)=4000,P=0.046,leftχ^(2)=4000,P=0.046;12 months:Rightχ^(2)=4000,P=0.046,leftχ^(2)=4000,P=***,there was no significant difference in motor functions based on WeeFIM results(P>0.05).GMFCS and MACS scores differed significantly at 12 months after the intervention(P=0.046,P=0.046).Finally,there was no significant change in cognitive functions(P>0.05).CONCLUSION In light of our findings,we believe that UC-MSC therapy has a positive effect on spasticity

关键词： Cerebral palsy Mesenchymal stem cell Transplantation Wharton’s jelly Muscle spasticity

Safety and efficiency of Wharton’s Jelly-derived mesenchymal stem cell administration in patients with traumatic brain injury:First results of a phase I study

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World Journal of Stem Cells 2024年第6期16卷 641-655页

作者： Serdar Kabatas ErdinçCivelek Osman Boyalı Gülseli Berivan Sez.n Omer Oz.emir Yeliz.Bahar-Oz.emir Necati Kaplan eyüp Can Savrunlu Erdal Karaöz Department of Neurosurgery University of Health Sciences TurkeyGaziosmanpaşa Training and Research HospitalIstanbul 34360Türkiye Center for Stem Cell&Gene Therapy Research and Practice University of Health Sciences TurkeyIstanbul 34255Türkiye Department of Neurosurgery University of Health SciencesGaziosmanpaşa Training and Research HospitalIstanbul 34255Türkiye Department of Physical Medicine and Rehabilitation Health Sciences University Sultan Abdulhamid Han Training and Research HospitalIstanbul 34668Türkiye Department of Neurosurgery Istanbul Rumeli UniversityÇorlu Reyap HospitalTekirdağ59860Türkiye Department of Neurosurgery Nevşehir State HospitalNevşehir 50300Türkiye Center for Regenerative Medicine and Stem Cell Research&Manufacturing(LivMedCell) Liv HospitalIstanbul 34340Türkiye Department of Histology and Embryology Istinye UniversityFaculty of MedicineIstanbul 34010Türkiye Center for Stem Cell and Tissue Engineering Research and Practice Istinye UniversityIstanbul 34340Türkiye

BACKGROUND Traumatic brain injury(TBI)is characteriz.d by a disruption in the normal function of the brain due to an injury following a trauma,which can potentially cause severe physical,cognitive,and emotional *** cell transplantation has evolved as a novel treatment modality in the management of TBI,as it has the potential to arrest the degeneration and promote regeneration of new cells in the ***’s Jelly-derived mesenchymal stem cells(WJ-MSCs)have recently shown beneficial effects in the functional recovery of neurological *** To evaluate the safety and efficiency of MSC therapy in *** We present 6 patients,4 male and 2 female aged between 21 and 27 years who suffered a *** 6 patients underwent 6 doses of intrathecal,intramuscular(i.m.)and intravenous transplantation of WJ-MSCs at a target dose of 1×106/kg for each application *** was assessed using the Modified Ashworth scale(MAS),motor function according to the Medical Research Council Muscle Strength Scale,quality of life was assessed by the Functional Independence Measure(FIM)scale and Karnofsky Performance Status *** Our patients showed only early,transient complications,such as subfebrile fever,mild headache,and muscle pain due to ***,which resolved within 24 *** the one year follow-up,no other safety issues or adverse events were *** 6 patients showed improvements in their cognitive abilities,muscle spasticity,muscle strength,performance scores and fine motor skills when compared before and after the *** values,which we used to assess spasticity,were observed to statistically significantly decrease for both left and right sides(P<0.001).The FIM scale includes both motor scores(P<0.05)and cognitive scores(P<0.001)and showed a significant increase in pretest posttest *** difference observed in the participants’Karnofsky Performance Scale values pre and post the intervention was statistically si

关键词： Traumatic brain injury Wharton Jelly Stem cell therapy Transplantation Mesenchymal stem cell

Post-layout simulation driven analog circuit siz.ng

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Science China(Information Sciences) 2024年第4期67卷 289-300页

作者： Xiaohan GAO Haoyi z.ANG Siyuan YE Mingjie LIU David z.PAN Linxiao shen Runsheng WANG Yibo LIN Ru HUANG School of Integrated Circuits Peking University School of Computer Science Peking University Department of Electrical and Computer Engineering University of Texas at Austin Institute of Electronic Design Automation Peking University

Post-layout simulation provides accurate guidance for analog circuit design, but post-layout performance is hard to be directly optimiz.d at early design stages. Prior work on analog circuit siz.ng often utiliz.s pre-layout simulation results as the optimiz.tion objective. In this work, we propose a post-layoutsimulation-driven(post-simulation-driven for short) analog circuit siz.ng framework that directly optimiz.s the post-layout simulation performance. The framework integrates automated layout generation into the optimiz.tion loop of transistor siz.ng and leverages a coupled Bayesian optimiz.tion algorithm to search for the best post-simulation performance. Experimental results demonstrate that our framework can achieve over 20% better post-layout performance in competitive time than manual design and the method that only considers pre-layout optimiz.tion.

关键词： analog EDA transistor siz.ng Bayesian optimiz.tion post-layout simulation

Rational Solutions of First Order Algebraic Ordinary Differential Equations

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Journal of Systems Science & Complexity 2024年第2期37卷 567-580页

作者： FENG Shuang shen Liyong School of Physical and Mathematical Sciences Nanjing Tech UniversityNanjing 211816China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

Let f(t,y,y')=∑ _(i=0)^(n )a_(i)(t,y)y'^(i)=0 be an irreducible first order ordinary differential equation with polynomial *** in 1998 proved that there exists a constant C such that every rational solution of f(t,y,y')=0 is of degree not greater than *** show that this degree bound C depends not only on the degrees of f in t,y,y' but also on the coefficients of f viewed as the polynomial in t,y,y'.In this paper,the authors show that if f satisfies deg(f,y)0,then the degree bound C only depends on the degrees of f in t,y,y',and furthermore we present an explicit expression for C in terms of the degrees of f in t,y,y'.

关键词： Degree bound first order AODE height rational solution

Solid-state Circuit Breaker Based on Cascaded Normally-on SiC JFETs for Medium-voltage DC Distribution Networks

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Protection and Control of Modern Power Systems 2024年第2期9卷 32-46页

作者： Dong He Haohui z.ou z.eng Lan Wei Wang Jinhui z.ng Xueping Yu z.John shen Chongqing University of Posts and Telecommunications ChongqingChina Henan Polytechnic University JiaozuoChina College of Electrical and Information Engineering Hunan University of TechnologyZhuzhou 412007China Hunan University ChangshaChina College of Electrical and Information Engineering Hunan UniversityChangshaChina College of Electrical Engineering Three Gorges University Rensselaer Polytechnic Institute TroyNYUSA

Solid-state circuit breakers(SSCBs)are critical components in the protection of medium-voltage DC distribution networks to facilitate arc-free,fast and reliable isolation of DC ***,limited by the capacity of a single semiconductor device,using semi-conductor-based SSCBs at high voltage is *** study presents the details of a 1.5 kV,63 A medi-um-voltage SSCB,composed primarily of a solid-state switch based on three cascaded normally-on silicon car-bide(SiC)junction field-effect transistors(JFETs)and a low-cost programmable gate drive *** and static voltage sharing among the cascaded SiC JFETs of the SSCB during fault isolation is realiz.d using the pro-posed gate drive *** selection conditions for the key parameters of the SSCB gate driver are also ***,an improved pulse-width modulation cur-rent-limiting protection solution is proposed to identify the permanent overcurrent and transient inrush current associated with capacitive load startup in a DC distribu-tion *** the developed SSCB prototype and the fault test system,experimental results are obtained to validate the fault response performance of the *** Terms—Solid-state circuit breaker,DC distribu-tion network,SiC JFET,voltage balancing,inrush current.

关键词： Solid-state circuit breaker DC distribu-tion network SiC JFET voltage balancing inrush current

Improving surface integrity of micro-holes in ECDM using ultrahigh-speed rotary of tool cathode and non-water-based electrolyte

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Chinese Journal of Aeronautics 2024年第5期37卷 506-519页

作者： Jiwen shen Weijing KONG z.engyang XU Yongbin z.NG Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The surface integrity of metal micro-hole structures produced by electrochemical discharge machining is unsatisfactory owing to the insufficient reaction area and strength of electrolysis action.A novel ultrahigh-speed Rotary Electrochemical Discharge Machining(R-ECDM)using non-water-based electrolyte is proposed to improve surface integrity by changing the breakdown medium of spark discharge and increasing the reaction area and strength of electrolysis.A mathematical model was developed to establish the relationship between rotational speed and forces acting on the *** on the magnitude of forces,controlling rotational speed changed the behavior and departure radius of bubbles on the cathode ***-speed photographs validate that,in the mathematical model,the number and departure radius of bubbles on the cathode surface gradually decrease with the increase of rotational *** experimental results show that the roughness(Ra)of the micro-hole sidewall decreases from 2.54μm to 0.20μm when the rotational speed increases from 500 r/min to 40000 r/*** length loss and wear ratio of the cathode are only 9.75μm and 6.5%,***,the micro-holes array with recast-free and surface roughness of 0.20μm is fabricated,demonstrating that the proposed approach contributes to improving surface integrity of metal micro-holes.

关键词： Electrochemical discharge machining Micro-holes Recast layer Ultrahigh-speed rotary Bubbles Force analysis Non-water-based solution